On Tue, Oct 18, 2016 at 2:35 PM, Ximin Luo <infini...@pwned.gg> wrote:
> Richard Biener:
>> On Mon, Oct 17, 2016 at 11:44 PM, Mike Stump <mikest...@comcast.net> wrote:
>>> On Oct 17, 2016, at 2:38 PM, Ximin Luo <infini...@pwned.gg> wrote:
>>>> Mike Stump:
>>>>> On Oct 17, 2016, at 11:00 AM, Ximin Luo <infini...@pwned.gg> wrote:
>>>>>> Therefore, it is better to emit it in all circumstances, in case the 
>>>>>> reader needs to know what the working
>>>>>> directory was at compile-time.
>>>>> I can't help but wonder if this would break ccache some?
>>>> Could you explain this in some more detail? At the moment, GCC will 
>>>> already emit DW_AT_name with an absolute path (in the scenario that this 
>>>> patch is relevant to). How does ccache work around this at the moment? 
>>>> (Does it use debug-prefix-map? In which case, this also affects 
>>>> DW_AT_comp_dir, so my patch should be fine.)
>>> If you compile the same file, but in a different directory, I wonder if cwd 
>>> will cause the cache entry to not be reused.
>>> I expect one of the ccache people that are around would just know if it 
>>> will care at all.
>> I believe ccache compares preprocessed source, definitely _not_ DWARF
>> output, so this shouldn't break anything there.
>> It might result in different object file output but as the reporter
>> figured due to a bug in dwarf2out.c we end up generating
>> DW_AT_comp_dir in almost all cases already.
>> I think the patch is ok but it misses a ChangeLog entry.  How did you
>> test the patch? (bootstrapped and tested on ...?)
> Thanks, I'll add the Changelog entry. My computer isn't very powerful, so I 
> didn't bootstrap it yet, I only tested it on a stage1 compiler, on Debian 
> testing/unstable. I'll find some time to bootstrap it and test it fully over 
> the next few days.
> Shall I also get rid of the Darwin force_at_comp_dir stuff? Looking into it a 
> bit more, my patch basically obsoletes the need for this so I can delete that 
> as well.

That would be nice.


> X
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